COMPRESS
Sintassi
COMPRESS(stringa_da_comprimere)
Spiegazione
Comprime una stringa e restituisce il risultato come stringa binaria. Questa funzione richiede che MariaDB sia stata compilata con una libreria di compressione, come zlib. Altrimenti il valore restituito sarà sempre NULL. La stringa compressa potrà essere decompressa con UNCOMPRESS().
Esempi
MariaDB [(none)]> SELECT LENGTH(COMPRESS(REPEAT('a',1000)));
+------------------------------------+
| LENGTH(COMPRESS(REPEAT('a',1000))) |
+------------------------------------+
| 21 |
+------------------------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS(''));
+----------------------+
| LENGTH(COMPRESS('')) |
+----------------------+
| 0 |
+----------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS('a'));
+-----------------------+
| LENGTH(COMPRESS('a')) |
+-----------------------+
| 13 |
+-----------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS(REPEAT('a',16)));
+----------------------------------+
| LENGTH(COMPRESS(REPEAT('a',16))) |
+----------------------------------+
| 15 |
+----------------------------------+
1 row in set (0.00 sec)
MariaDB [(none)]>
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